Explanation:
Cynthia should be diagnosed with Cyclothymia.
According to the question, Cynthia is moody and shows short periods of mood swings. Her mood changes spontaneously and then she gets normal. This might be confused as bipolar disorder but it is not so because bipolar disorders is characterized by long episodes of particular mood states. Secondly, Cynthia is able to lead a normal life. So, she is suffering from Cyclothymia.
